New WebKit builds offer scrolling relief for retina MacBook Pros

Tests show a newer build can offer more than twice the fps on laggy sites.

Retina MacBook Pro owners who have been frustrated at slow Safari performance may find some relief in the recent WebKit nightly builds. The discovery was originally dug up by a MacRumors forum post and tested by AnandTech on Tuesday, showing a significant increase in frame rates when scrolling through certain sites, such as Facebook.

AnandTech put one of the recent builds to the test on a 13-inch MacBook Pro with retina display running Mountain Lion at 1440x900 (AnandTech used version r135516, though the most recent build as of publication is version r136460). Using Quartz Debug to look at the differences in frame rate, the site saw the average of sites like Facebook more than double, from an average of around 20fps to around ~47fps. But this "fix" only applies to media-heavy sites that previously caused the MacBook Pro to choke up—when testing on sites that otherwise performed fine in Safari on the retina MacBook Pro, performance remained roughly the same.

According to the MacRumors forum thread, Apple plans to eventually release a full version of Safari with this level of optimization, so if you're wary of running prerelease builds of WebKit, you may not have to wait long. But if you're a retina MacBook Pro user whose blood pressure ticks up every time Safari gets laggy, the nightly build could offer you sweet, sweet relief until the next major Safari release comes down the pipeline.

Jacqui Cheng
Jacqui is an Editor at Large at Ars Technica, where she has spent the last eight years writing about Apple culture, gadgets, social networking, privacy, and more. Emailjacqui@arstechnica.com//Twitter@eJacqui

20 Reader Comments

While I find the staggery scrolling mildly annoying on some sites (The Verge is my worst "offender"), I'm mostly interested to see what's changed in order to improve this. Hopefully the Webkit blog will knock something up, or someone will be able to do some code analysis.

But if you're a retina MacBook Pro user whose blood pressure ticks up every time Safari gets laggy, the nightly build could offer you sweet, sweet relief until the next major Safari release comes down the pipeline.

This is me.

Apple's highest end laptop can't do Facebook as well as the cheapest Windows laptop...? (although breezes through everything else).

It's like the weird animated GIF bug in non-Intel versions of Mac OS X that prevent those computers from running hamster dance as smoothly as computers from the late 90s.

Still has lag outside of browsers too though. The calender flip animation you can literally count out the frames on. The green button resize is sometimes slow too, although that one is harder to notice unless you have a newish non-retina machine to compare side by side.

I am one of the most picky people I know when it comes to lag and smoothness, I had a CRT for gaming for the longest time until 120hz LCDs came out. But I just can't understand why people are so negative about the retina macs, the picture quality second to none, it's not even close.

Even with the UI lag, I am never going back to regular screen. Retina is well worth it.

Since this is a WebKit fix and not a Safari fix, it is only a matter of when the Chrome team decides to pull in the code and ship out an update.

That's assuming that the fixes in question are in parts of the WebKit codebase that are shared between Safari and Chrome. There are numerous places where Safari and Chrome use different paths for the same function because they weigh the trade-offs differently (one such trade-off would be on leveraging OS support vs ensuring consistency across different OSs).

But if you're a retina MacBook Pro user whose blood pressure ticks up every time Safari gets laggy, the nightly build could offer you sweet, sweet relief until the next major Safari release comes down the pipeline.

This is me.

Apple's highest end laptop can't do Facebook as well as the cheapest Windows laptop...? (although breezes through everything else).

It's like the weird animated GIF bug in non-Intel versions of Mac OS X that prevent those computers from running hamster dance as smoothly as computers from the late 90s.

Apple can be weird sometimes...

You got it wrong, Apple is not lagging on a basic level... Rendering on a retina display is much more compute intensive compared to the cheap displays that usually have seen windows with. Apple has pushed the hardware out and gradually scaling out the bits.... you need to walk into a Apple store and see a retina display before comparing it with anything.

Or Apple could use a dpi system which didn't cause such problems, like Android and Windows.

Apple tried to push resolution indipendence for years, when Windows doesn't scaled at all and Android was a just a human being with robotic parts. Developer never followed. Everyone embraced retina that's actually a smarter way app wise to manage high resolutions, developing 2x assets for applications is doable with far less problems and time. Efficiency always win. Also, it's not like scrolling and ui responsiveness is better on windows with that sort of resolution (if a computer with that resolution exists in the windows world, don't think so).

As long as you're willing to live with top-level UI at 144 DPI and just scale the *content* to 196 DPI, Windows 8 and IE10 in particular work very well. The 144 DPI suggestion isn't so much of a technical limitation as a UI art issue, where I don't think people expected such a sudden jump in DPI.

By default applications that don't declare themselves as DPI-aware will get scaled by the DWM using raster scaling, like OSX, but you can change this by opting in to "Windows XP Style" DPI scaling. IE is DPI-aware, so it'll render the same either way. At 144 DPI the default zoom is 150%, but I prefer 200% most of the time. The setting sticks.

As of a couple months ago, when on battery there was scrolling sluggishness with the default Boot Camp drivers, but this is fixed by installing the latest NVIDIA drivers.